JPS6113140A - Quantitative analysis of iron by plasma luminous analysis - Google Patents

Abstract

PURPOSE:To perform rapid and accurate quantitative analysis of iron contained in an arrestor element, etc. protecting an electric communication device, etc. from a shock voltage, by measuring a luminous intensity at a wave length of 2,382Angstrom . CONSTITUTION:Subjecting a specially prepared specimen reagent to a plasma luminous analysis for measurement of a luminous intensity at a wave length of 2,382Angstrom , iron content is calculated by predetermined calibration curve and cobalt correction value. The calibration curve is so drawn that to an aqueous solution containing zinc oxide 2.38g, boric acid 1g, concentrated hydrochloric acid 20ml, concentrated hydrofluoric acid 0.5ml per 100ml water iron is added in a quantity of 0.5, 1.0, 3.0 and 0.5mg respectively for 4 kinds of aqueous solution. Further, the correction of cobalt is so made that, concerning a specimen prepared by the specified method, a value DELTAFe of a measured value less a theoretical value is obtained and a correction formula is developed from a co-relationship between said value and added amount of cobalt.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] The present invention relates to a method for quantitatively analyzing iron using plasma emission.

[Technical Background] Abnormal voltages generated by lightning strikes, etc., or induced voltages generated by such abnormal voltages often destroy telecommunications equipment. Even if the voltage is not as high as lightning, the shock beyond the permissible voltage can cause problems for electronic equipment, and to prevent this from happening, it is necessary to insert all arrester elements between the line and the ground or between the lines. It is commonly done.

This arrester has two electrodes facing each other with a gap such as an insulator or an air gap between them, and when an abnormal voltage is applied, a discharge occurs between the electrodes to prevent problems from reaching the main circuit. It is something that exists.

By the way, in order to stabilize the quality of arrestor elements used for such purposes, it is of course necessary to understand the components in the element material. When analyzing the fluorescent X-ray spectrum, iron is always detected even though all iron is not added to the arrester element.

It is currently unclear whether this iron contamination is caused by contamination during the manufacturing process or by being included in the raw materials from the beginning. In any case, at present, even if the arrester element contains a small amount of iron, the element characteristics are satisfied, but if the allowable amount of iron could be clearly determined, there would be no need to prepare high-grade raw materials unnecessarily. Therefore, it is possible to reduce the cost of the arrester element.

[Purpose of the invention]

The purpose of the present invention is to establish a quantitative analysis method for iron necessary for fully confirming the relationship between element characteristics and the allowable limit amount of contained iron as described above. It provides law.

[Summary of the invention]

The present invention has been achieved through studies to achieve all of the above objectives, and is based on plasma emission analysis + c
This invention relates to a method for quantifying iron by plasma emission spectrometry, which involves measuring the luminescence intensity at a wavelength of 238.2 nm (2382X) and calculating the iron content using a calibration curve and a cobalt correction value.

When performing plasma emission analysis, the analytical line (wavelength used)
It is necessary to determine the emission intensity, and it is desirable that the emission intensity is within the concentration range for quantitative analysis, and that the emission spectrum of interfering elements is not distorted or close to each other.

To determine this analytical line, the sample aqueous solution was prepared in accordance with the following sample dissolution method, and the analytical line was determined.

(2) Preparation of sample solution Weigh out 3 g of the finely ground sample and place it in a pressurized Teflon crucible and add 20 ml of concentrated hydrochloric acid. Concentrated hydrofluoric acid 0.5ml k
;C(7) Add a stirrer to the crucible, hold the entire crucible in a stainless steel container, and seal the container.

It is preferable to stir the crucible on a stirrer to even out the crucible contents before heating the crucible.

Thereafter, this crucible was heated to 120°C for 1 hour (no stirring).

A cycle consisting of stirring for 30 minutes is performed twice to dissolve the sample by heating for a period of time, and after cooling the crucible to room temperature, the entire solution in the crucible is transferred into a polyolefin beaker. This beaker was completely filled with 1 g of boric acid, heated on a hot water bath to dissolve the boric acid, cooled to room temperature again, transferred to an IQQm7 glass volumetric flask, and added the beaker washing solution. Add water up to the line to make the sample solution.

■1 Determination of analytical line Actual sample or standard solution containing only iron? Comparison of emission spectra used? I went, but the emission spectrum line 238 of iron
．． When using the actual sample purple for the fc iron spectrum (Figure 1) expressed at 2n- (2382X), another peak It was done.

As a result of investigation, it was found that this peak X is an emission spectrum line of cobalt, but on the other hand, it is found that the next peak emission intensity appears in the 239.6n envelope (2396x) band (Figure 4).
As a result of a sound examination, emission spectrum lines of other elements were observed as shown in Figure 5, and it was determined that this line was based on nickel (Figure 6).

Figure 2 shows the effects of cobalt and nickel on the emission spectrum of iron! Judging from the M distribution of the spectra in Figure 1g5, there is less overlap when using 238.23-r2382'A), so this wavelength is used as the analysis line.

■The iron content in the calibration curve arrester element is about KIQppm, so the iron content is 5.10.30.50ppm.
When 3N HCl of m was prepared and the linearity of the calibration curve was examined, a straight line as shown in Figure 7 (1) was obtained. The results were obtained: correlation coefficient R = 0.99999°, standard deviation (sc) in terms of concentration = O, D1 (ppm).

(2) Influence of reagents and coexisting elements. The concentration of iron was set to 10 ppm, and the total luminescence intensity of iron in the samples was measured by changing the temperature of the target element.
Content from the calibration curve? The ratio to the iron concentration was determined.

1) Bis=r Su: 1500, 2000 and 25
The iron recovery rate when 00 ppm Bi (i7) is included is as follows, and it can be considered that there is no influence of B1. The relationship between the iron recovery rate and the allowable range is shown in Figure 8. The vertical axis is Fe Recovery rate (-, e Rec, %), the range shown by the broken line shows the allowable range.

Actual Fe value ppm 10. IQ 10.03
10.10Fe theoretical value ppm 10.00 1
0.00 10.00Fe recovery rate% 101.0
．． 100.3 101.02) Cobalt: 1oo
, a6.2oo, ss and 301.29ppm Co
The recovery rate of iron when containing f is as follows, and CO
It was observed that the recovery rate of iron increased as the amount of iron added increased.

Actual Fe value ppm 12.26 14.17
16.26Fe theoretical value ppm:' 10.00
10.00 10.00Fe recovery rate% 122.
6 141.7 162.6 Shown in Figure 9 of Yuito 7 in the table above.

) Silicon: 50,100 and 15Qppm S
Although it was recognized that the ie added 0゛ caused negative interference, it was recognized that it was within the permissible range. The results are shown in Figure 10.O Fe measurement ppm 9.91 9.97
9.91Fe theoretical value ppm 10.00 1
0.00 10.00Fe recovery rate% 99.1
99.7 99.14) Aluminum: 2,6
and 4 ppm At'l- were added.

Fe measurement value ppm 9.95 10.08
10.08Fe theoretical value ppm 10.00 10
．． 00 10.00Fe recovery rate% 99.5
100.8 100.8 This relationship is shown in Figure 11.

5) Nickel: 200, 300 and 400ppm
of Ni was added.

Fe measurement value ppm 9.89 10.08
9.89Fe theoretical value ppm 10.00 10
．． 00 10.00Fe recovery rate% 98.9 1
oo, s 98.9 This relationship is shown in FIG.

6) Chromium: 2/i6. A, 592.8 and 73
9.2 ppm of Crf was added. It was observed that the iron recovery rate increased as the amount of Cr added increased. Figure 16 shows the behavior.

Cr addition fjt ppm 2d6. il
592.8 739.2 Fe measurement value ppm
10.97 1167 12.32Fe theoretical value pp
m 10. OQ 10.00 10.0Q
Fe recovery rate % 1[]9.7 116.7 1
23.27) Copper: 0.5, 1.0 and 1.5 ppm
of Cui was added.

Fe measurement value ppm 9.91 9.97 1
0.03Fe theoretical value ppm 10.00 10.0
0 10.00Fe recovery rate% 99.1'
99.7 100.3 This relationship is shown in Figure 14.

8) Zirconium: 1, 6 and 5 pPm of Zr were added.

Fe measurement value ppm 10. Qro 10.22 1
0.09Fe theoretical value ppm 10.00 10.0
0 10.00Fe recovery rate% 100. Ro 1 [)
2.2 100.9 This relationship is shown in Figure 15. As a result, it was observed that the tear recovery rate tended to decrease as the amount of Mn added increased, but the amount was small and the effect could be ignored.

Fe measurement value ppm 9.92 9.86
975Fe, theoretical value ppm 10.00 10.0
0 10.00Fe recovery rate% 99.298.6
97.5 This relationship? It is shown in FIG.

10) Antimony: 2500, 3000 and 650
A total of 0 ppm of sb was added.

Fe measurement value ppm 9.81 9.53
9.53Fe theoretical value ppm 10.00 10.
00 10.00Fe recovery rate% 98.1 9
5.3 95.3 This relationship? It is shown in FIG.

11) Zinc oxide: 2.0, 2.5 and 6.0 town Z
When nOf was added, no negative effects were observed as shown, but this was due to a decrease in the amount of sample suction due to an increase in the viscosity of the solution, a decrease in atomization efficiency, and a decrease in the amount of sample absorbed into the plasma. This is considered to be due to a decrease in introduction efficiency, etc. (Fig. 18).

Fe measurement value ppm 9.72 9.72
9.92Fe theoretical value ppm 10.0
0 10.00 10.00Fe recovery rate %
972 972 992 Cobalt is iron,
It is clear from the results in Figure 6 that it has a positive effect on the analytical line of It is not in the position. Therefore, it is thought that the positive shadow # that appears when all chromium is used is due to the iron mixed in the chromium.

V. Removal of interfering factors 1) Zinc oxide Since the interfering cause is due to the viscosity of the m solution, it is corrected by mixing the same amount of zinc oxide in the actual sample solution into the standard solution for creating the calibration curve.

2) Subtract the total value of the theoretical value (feeding amount, Fe) from the measured value of cobalt iron (Fe) and calculate the correlation with the amount of cobalt added. The error due to the influence of cobalt is Fe'-Fe- △F
e rppm) and the value of 2)? Use △Fe
Correlation between and cobalt '11klf(X)? When I calculated it, I got Figure 21. Here, correlation coefficient R = 0.9999° Correlation formula Fe (ppm) = '1.99X 1O-2X
+0.23. The standard deviation S2 was 0.07 (ppm), indicating a very good correlation.

From the previous two equations, Fe (ppm) = Fe' - (1,99
x I Q-2-X +0.25) is obtained.

This formula? The following table shows the data of LV and 2) all corrected using the above-mentioned LV.

Fe' 12.26 14.17
16.26Fe correction value (ppm) 10.03
9.94 11J, 03Fe corrected recovery rate c%)
100.3 99.11 100.
3. FIG. 22 is a diagram illustrating the Fe recovery rate before the correction and the recovery rate after the correction.

3) Chrome Quantitative analysis of iron in chromium was performed using the standard addition method.

Specifically, the calibration # of the iron standard solution shown by the A line in Figure 26
(represented by the formula 1 = 29'r6C + 4A), 400 ppm' of chromium' (i = iron' (zlo
Plot the luminescence intensity when adding , 20 and 30 ppm. BKfa, I = 28.81c + 40.
6) Both (7J) slope f: Comparison 17k were almost the same (slope ratio -288, 1/293.6 = 0.98), confirming that there was no influence of the matrix.

From this, iron can be determined by subtracting the background of the iron standard solution and using the standard addition method calibration curve (A O, 6
-4,11/28.81= 1.27 (ppm), which is converted to iron in chromium (1,27/1l
DO), x100=0.32% was obtained. Therefore, the influence of chromium can be corrected by subtracting the difference in iron in chromium (-) from the measured value.

[Embodiments of the invention]

Example 1゜ calibration curve 1001? 2.38g of zinc oxide and 1g of boric acid per liter.

Concentrated hydrochloric acid 2Qm4 dihydrofluoric acid 0.5ml? ! −
Add each 'zo' to the iron in the aqueous solution, 5, 1. 0. 3. 0, 5.
0 = gzut i6"2 plus fc l 4M solution was used to create a stimulant wire bK. I = 153.6C + 13.5
．． Correlation coefficient R=0.9999. The standard deviation in terms of concentration Sc was 0.035 (mg), indicating good linearity.

In addition, Na
2003 212mg was added to make the concentration the same.

Analysis of pseudo samples All 5 samples were adjusted with fc group composition as shown in the following table (-1) The iron concentration was calculated using the above calibration curve.

+: Created from O, AN, N.2C03 solutions; all other elements were created from HCI solutions.

Apparent iron content due to the influence of cobalt: 0.353 mg
.

Iron Q in chromium (99,99%2 display), 125mg
A total of 0.4'78 mg k was subtracted from the measured value, showing very good agreement with the iron charge value.

Tatami: CV (%) = (s/-) x 1o.

Example 2 Five samples were taken from the same arrester element, and the samples were prepared with bamboo shavings according to the procedure described in (1).The iron concentration in each sample was determined using a radiation tube. The cobalt content in this element was determined in advance using fluorescent X-rays, and the correction formula F
e (ppm) =Fe'-(1,99X 10''2・x
+0.23)k was used to correct the measured values.

As a result, the iron content (pprr+
) obtained the following values.

Number of samples N = 5 Average of F e Mffl in the element M -68,8 (pp
m) Standard deviation S-6,11 Coefficient of variation CV=4.52 (%) From the above results, it is an extremely effective means for quantifying the iron content in arrester elements, and specifically, For example, analysis can be performed using the following procedure.

Sample Preparation (2) Arrester element: After pulverizing f with an alumina pestle, place it in an agate container and pulverize it with a vibrating mixing mill.

■ Weigh out approximately 3g of sample powder accurately and place it in a pressurized crucible.

■ Concentrated hydrochloric acid 2D in a pressurized crucible? +lt, concentrated hydrofluoric acid Q, and 5 mA. At this time, be careful not to scatter the sample powder that was added earlier. Then, add a stirring bar, seal the container, and stir for 1 minute to make the solution uniform.

(2) After heating at 120°C for 1 hour, stir the crucible for 30 minutes with the stirring bar in the crucible rotated (-) on the starboard.

This is repeated for 2 cycles for a total of 6 hours to dissolve the sample.

■ After cooling the crucible, put the sample solution into a poly beaker.
Furthermore, the crucible is washed with water and the washing liquid is also placed in the same plastic beaker.

(Put all 1g of boric acid into a beaker, then add all 90 g of boric acid to the beaker.
Dissolve boric acid by heating in a water bath at °C. After cooling the solution, transfer it to a 1 ooml glass flask, make the volume constant with water, and immediately transfer it to a polyester sample bottle after fC.

■ 2.38g of zinc oxide with a purity of 9999% or more mixed with 1 part of boric acid
g'Th, weigh each into 4 poly beakers.

■ Add the indicated amount of concentrated hydrochloric acid to make a total of 90% zinc oxide and boric acid.
Dissolve by heating in a water bath at °C.

(Milk) Cool 1 table and add to 0.5 ml' of concentrated hydrofluoric acid.

■ 25m from atomic absorption iron standard solution 11000pp
Take A fraction, add Sml of concentrated hydrochloric acid to make the volume constant to 50ml, and prepare a 5DOppm iron standard solution. 1°2.6 from there
．． Aliquot 10ml and place it in a 1ooml volumetric flask in advance.

■ Transfer the solution in ■ to the volumetric flask in ■, and wash the poly beaker with water [and then pour the washing solution into the same volumetric flask. Make the volume constant with water.

acid ppm g groove t
g ηIt5 2.38
19.9 1.0 0.5ID
2.38 19.8 1.
0 0.5602.3819. ,! 11.00
．． 55 [) 2.38 19. o
1.0 0.5 (p) 2.38 g of pure zinc oxide of 4N or higher and 1 g of boric acid were collected in three poly beakers.

(Add concentrated hydrochloric acid in the indicated amount below, and dissolve zinc oxide and boric acid by heating in a 90°C water bath.

■ After cooling, add 0.5 ml of concentrated hydrofluoric acid.

3) Atomic absorption iron standard solution 11000pp to 25fi
t fraction, add 5 ml of concentrated hydrochloric acid and make the volume constant to 50 ml.
Prepare a 0 ppm standard solution, take 2 tnL from it and put it into a 100 ml glass volumetric flask.

(5) Metal Kohar) - (99,99%, indicated) 2
．． 0 g′? f: Hydrochloric acid 2 Hydrochloric acid 2 Prepare a standard solution with a concentration of 20,000 ppm. Aliquot 10.20 and 3QmA from this bath liquid and place them in the glass volumetric flask mentioned above.

Transfer all of the solution of Ω ■ to ■, and then add it to the poly beaker? Wash with water and add the washing solution to the same volumetric flask. Immediately after adjusting the volume with water, transfer to a plastic sample pin.

Tlpm gml g ml
ppml00 Z38 19.8 1st
0.5 1.0200 2.38 19
．． 8 1.0 0.5 1.0300
2, Ro8 19.8 1. rl
O, 5' 1.0 Cobalt correction method (reverse 5, luminescence in standard solution for production, severity 238
Measure at 2λ and prepare iron calibration Mk.

■ Measure the luminescence intensity of iron in the six samples prepared in the section on preparation of samples for creating the correction formula for cobalt, and find the concentration from the @ dose curve in ■.

(Difference tΔF' from the actual value of ferrugin (10 ppm) added in section ① of preparing the sample for creating the correction formula for cobalt)
Let e, and find the relational expression between ΔFe and CO concentration.

Yu9 Cobalt oxide A (C
O2O3) is determined.

・Convert Co2O3υ1 to cobalt a IJt.

=0.711A(%) 0 Find the amount of cobalt in the sample.

/, 11x10-"
The influence of cobalt can be removed by subtracting △FQf from @
Ru.

■　The operation should be performed for each measurement.

The flow sheet of the above analysis procedure is shown in FIG. 21.

〔Effect of the invention〕

By implementing the present invention, q.) The sample was easily dissolved by placing the sample, concentrated hydrochloric acid, hydrofluoric acid, and a stirring bar in a pressurized crucible, heating the crucible, and stirring the whole bar by repeating the process.

■ Concentrated hydrochloric acid for standard solution and actual sample solution.

By combining the acid concentration 7 of concentrated hydrofluoric acid and boric acid,
That influence? Removed.

■Glass @ (contains ICP) tongue/corrosive hydrofluoric acid 1 boron.

Masked with acid.

■ ICP? for direct quantification using the calibration curve method.
Accurate values can be obtained in a short time.

■ Since the iron analysis line overlaps the cobalt analysis line, the apparent measured value of iron increases in proportion to the amount of cobalt. For this reason, we created a correction formula for cobalt and corrected all its effects.

With this feature, iron, which is an impurity in the shredded 17 Leicester element, can be quickly and accurately quantitatively analyzed.

(2) Accurately carry out raw material acceptance, product quality control, and process control.

■ It is possible to fully analyze the effects of subtle changes in Tetsunomiya quantity on device characteristics. Therefore, the quality of the raw materials can be lowered within a range that does not adversely affect the characteristics of the element6, making it possible to significantly reduce costs.

This is a sound effect.

[Brief explanation of drawings]

Figures 1 to 6 are charts for plasma emission analysis, Figure 7 is a graph showing a calibration curve showing luminescence intensity versus iron concentration, and Figures 8 to 18 are interferences of various coexisting elements to iron analysis. Graphs showing the situation, Figures 19 and 2
Figure 0 is a chart of plasma emission analysis, Figure 21 is a graph showing the relationship between the iron analysis value minus all the preparation values and the amount of cobalt present, and Figure 22 is the graph before and after the correction made to the amount of cobalt. Graph showing the behavior of Fe recovery rate, 2nd
Figure 6 is a graph showing the behavior of luminescence intensity indicated by Fe concentration depending on the presence or absence of chromium, Figure 24 is a process diagram showing the method of preparing samples to be actually analyzed, and Figure 25 is a diagram for creating a calibration curve. It is a process diagram showing the entire preparation of the sample. Agent Patent Attorney Sanro Kimura Figure 4 Figure 5 - Ikuo Kei "' Figure 19 Figure 20 Figure 21 Co's edge cot (pprr+) Figure 22 COc Ling/Suppression (ppm) Figure 24 ICP (Shiga 2382 A) Figure 25

Claims (4)

[Claims] (1) Subject the sample solution to plasma emission analysis to obtain a wavelength of 238
．． Measure the emission intensity at 2 nm (2382′ Å),
A quantitative iron analysis method using plasma emission spectrometry, which involves calculating the iron content using a separately determined calibration curve and cobalt correction value. (2) Weigh out a certain amount of the pulverized sample that has reached a constant weight, place it in a Teflon pressurized crucible, add concentrated hydrochloric acid and concentrated hydrofluoric acid, mix the whole thing, heat and stir, dissolve the sample, and then place it in the crucible. Claim 1 describes the use of a sample solution obtained by cooling, washing the sample into a polyolefin beaker, adding boric acid, dissolving the boric acid on a hot water bath, cooling again, and diluting accurately using a volumetric flask. Quantitative analysis method. (3) Weigh 2.38 g of zinc oxide with a purity of 99.99% or higher and 1 g of boric acid into 4 polyolefin beakers, and add 19.9, 19.8, 19.4, and 19.0 ml of concentrated hydrochloric acid to each. Add to the beaker, heat and dissolve on a 90°C water bath, and after cooling, add 0.5 ml of concentrated hydrofluoric acid to prepare solution A.
ml was taken out and 5 ml of concentrated hydrochloric acid was added to make a 500 ppm iron standard solution, from which 1, 2, 6 and 10 ml were each taken into four 100 ml volumetric flasks to prepare the above four solutions A in the same way. The sample is washed into the volumetric flask and diluted to the marked line, and then subjected to plasma emission analysis at 238.2 nm (2382 Å) to measure the emission intensity and use a calibration curve obtained by plotting each concentration. Quantitative analysis method. (4) Weigh 2.38 g of zinc oxide with a purity of 99.99% or higher and 1 g of boric acid into three polyolefin beakers and add 19.8, 19.6 and 19.4 ml of concentrated hydrochloric acid.
were added to each, heated and dissolved on a 90°C water bath, and after cooling, 0.5 ml of concentrated hydrofluoric acid was added to prepare solution B. On the other hand, 25 ml was taken from the iron standard solution for atomic absorption, and 5 ml of concentrated hydrochloric acid was added to make 50 ml. A standard solution containing 500 ppm of iron was taken as a standard solution, and 2 ml of it was divided into three 100 ml volumetric flasks (solution C), and 2.0 g of 99.99% metallic cobalt was added separately.
Dissolve it in 20 ml of hydrochloric acid to make 100 ml to prepare a standard solution with a cobalt concentration of 20,000 ppm.
0 and 30 ml were added to each of the three volumetric flasks containing the three types of solutions C, and solution B was also added to make a constant volume by adding pure water up to the marked line. Claim 1, which comprises measuring the plasma emission intensity, determining the difference ΔFe between the charged iron concentration and the actual measurement value, deriving a correction formula from the relational expression between this and the Co concentration, and correcting the iron content. Quantitative analysis method described in section.